The present invention relates to an air bag device for a passenger disposed in a vehicle for expanding an air bag upon vehicle collision thereby protecting the passenger.
An air bag device for a passenger comprises a folded air bag and an inflator attached to a holding member, for example, a container, and a lid attached so as to cover the air bag. Upon vehicle collision, the inflator is actuated to extend the air bag. The lid is pushed by the inflating air bag and opens to the inside of a cabin, so that the air bag extends largely to the inside of the cabin thereby protecting an occupant.
FIG. 5 through FIG. 7 show an air bag device in the prior art, in which FIG. 5 is a schematic perspective view illustrating the entire constitution of the air bag before extension, FIG. 6 is a side elevational view and FIG. 7 is an enlarged perspective view.
In the air bag device 10, a lid 14 is attached in front of a box-shaped container 12 opened at its front. An inflator 16 is secured to the container 12. An air bag 18 is folded and inserted in the container 12 and fixed by bolts 19. A plurality of suction apertures 20 is perforated in an upper wall and a lower wall of the container 12 respectively. When the inflator 16 is actuated to jet out a gas into the container 12 and extend the air bag 18, atmospheric air flows through the suction apertures 20 and enters into the container 12 thereby rapidly extending the air bag 18.
The lid 14 comprises a back-up plate 22 made of an aluminum alloy or the like and a soft cover 24 disposed in front of the plate 22. The upper edge of the plate 22 constitutes a lid mounting portion 26 extended above the container 12.
A lid mount bracket 28 is secured to the upper surface of the container 12 by means of spot welding or the like. The lid mount bracket 28 extends along the upper surface of the container 12 and has a plurality of bolt apertures 30 perforated therein. A plurality of bolt apertures 32 is also perforated in the lid mounting portion 26, and the lid mounting portion 26 is secured by means of bolts 34 and nuts to the lid mount bracket 28.
As shown in FIG. 7, the rear face of the container 12 is concaved for receiving the inflator 16. Further, slits 36 are opened at the rear face for introducing the gas jetted out from the inflator 16 into the container 12. The inflator 16 is held by an inflator cover 38 to the container 12. The inflator cover 38 is secured by means of bolts 40 to the container 12. Reference numeral 42 denotes openings through which the bolts 40 pass.
When the inflator 16 is actuated to jet out the gas into the container 12 and the air bag 18 starts inflation, the lid 14 at first moves slightly forward by the air bag 18 as shown by the dotted chain 14a in FIG. 6 and then the back-up plate 22 deforms such that the lid 14 bends upwardly as shown by an arrow 14B.
When the air bag 18 is thus extended, the back-up plate 22 at first undergoes a forward force and an extremely large stress is exerted on the lid mounting portion 26.
The stress concentrates near the bolt apertures 32 that engage the bolts 34. Accordingly, it has been necessary for the portion in the vicinity of the bolt apertures 32 of the lid mounting portion 26 of the back-up plate 22 to be reinforced to have high strength. In addition, it has been necessary to dispose a plurality of bolt apertures 32 and secure by means of a plurality of bolts 34, which makes the assembling operation troublesome.